1. Field of the Invention
This invention relates generally to electrosurgical generator apparatus and more particularly, but not by way of limitation, to apparatus for controlling an alternating current signal generator so that either a first alternating current signal or a second alternating current signal is provided to a workpiece engaging means, such as a hand-held probe.
2. Description of the Prior Art
In the medical field of surgery it is known that electric current can be used in the surgical cutting and coagulation of tissue. For example, a sinusoidal radio frequency current signal may be used to cleanly cut tissue, whereas an intermittant, exponentially decaying sinusoidal radio frequency current signal can be used to quickly destroy tissue. Such electric currents can be applied to the tissue through a probe under control of either a foot-controlled switch or a finger-controlled switch. An example of an electrosurgical generator apparatus which is operated via a finger-actuated switch mounted in a hand-held probe is disclosed in U.S. Pat. No. 4,071,028 in the name of Perkins. Another example of a finger-actuated control unit for an electrosurgical generator is an apparatus manufactured under the name Aspen Labs.
Although the surgical use of electric current is well known and devices which use electric current to surgically cut and/or coagulate tissue have been proposed or manufactured, these devices fail to separately isolate a primary power supply from each of two electrically isolated circuits within the control unit of the electrosurgical generator apparatus; and they do not isolate, through alternating current actuated relays, control signals which are provided to an alternating current signal generator means from circuits of the control unit while also providing dual mode control signals from a single hand-held probe to select either of two surgically usable alternating current signals.